The present disclosure relates generally to the field of waveform generation. The present disclosure more particularly relates to power amplifiers (e.g., broadband power amplifiers).
Conventional broadband power amplifiers are used in a variety of waveform generation applications including electromagnetic communication systems (including radios, cellular phones, network devices, etc.), location devices, etc. According to one particular application, broadband power amplifiers are used in systems that can have high peak-to-average-power-ratio (PAPR) waveforms, such as orthogonal frequency division multiplexing (OFDM) and wideband code division multiple access (WCDMA) systems.
According to one example, conventional orthogonal frequency division multiplexing (OFDM) and wideband code division multiple access (WCDMA) systems often use radio frequency power amplifiers that exhibit power efficiencies under 20%. In addition, conventional power amplifiers can exhibit inefficiency and/or spectral non-compliance with wideband high peak-to-average-power-ratio (PAPR) waveform requirements, such as with Wideband Networking Waveform (WNW), FlexNet OFDM, Combat Data Link (CDL) and other waveform protocols. Low levels of power-efficiency can cause significant system limitations in size, weight, and operating time, or duty cycle, due to thermal constraints. In addition, low levels of power efficiency can limit the number of simultaneous signals which can be transmitted from a platform (e.g., airplane, mobile ground vehicle, helicopter, human-portable communication device, etc.) due to thermal constraints.
Various limited solutions exist for which operation can be restricted to a narrow range of frequencies (e.g., five percent bandwidth around operating frequency). Maintaining the necessary tolerances for successful operation of some of the solutions across an octave frequency range remains a challenge. Achieving high amplifier power-efficiency with high peak-to-average power ratio waveforms is difficult for a wide range of frequencies (e.g., 1 GHz to 2 GHz).
Progressive non-linearity of envelope tracking as radio frequency compression begins tends to limit the usefulness of envelope tracking techniques. The non-linearity requires complex distortion compensation schemes or limits improvements in power efficiency.
What is needed is a power amplification system and method that improves efficiency of the amplifier, covers wide frequency bands, and is suitable for handling multiple waveforms with low levels of distortion and noise output. Further still, there is a need for a power amplifier for use with wide band high peak-to-average-power-ratio (PAPR) waveforms. Yet further still, there is a need for a modulator that has higher efficiency and/or broad spectral performance. Yet further, there is a need for a linear high compression envelope tracking system and method. Still further, there is a need for a system for or a method of amplifying high PAPR waveforms with high efficiency. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.